Best 12AU7?

@olds1959special Not a fan of the Tung Sol re-issue when compared to NOS. But…they are probably one of the better new tubes. I also really like the RCA 5814a TM BP. Top 3 for me but I don’t see it brighter as you said you preferred. It more neutral  towards warmer to me which I prefer. Other good ones I like are Westinghouse ‘60’s long Carbon Plate and Raytheon ‘60’s 5814a TM BP.

I'd also say my 2nd in line behind the La Radiotechnique are the Brimar, CV 4003 gold pin. Its a heavy sound that is totally enjoyable. 100% opposite of the LR 12au7wa - they give my DAC a completely differnt perspective. That's what makes this fun... all the "better" tubes play great, they just come at you from differnt angles & give the presentation a decidely contrasting sound. 

I find it bright, but in a very nice, warm and fat way!

That seems like a contradiction in terms?

I call it fat because of the way it spreads out the sound. I call it warm because of the overall harmonic saturation. But it is basically bright, but more of a creamy, smooth bright!

olds1959special

As already mentioned, reach out to Brent Jessee.....he's the best tube provider I've ever used. He carries a great stock of tubes, but he doesn't give them away. The best 12AU7 tubes are expensive, so be prepared

STAY AWAY from re-issue tubes, go with NOS only

For emphasis on treble (as you indicated) I'd look at: Amperex (Holland made versions) 7316 1950s/1960s, Amperex E800CC/6085 (check with your amp manufacturer that these are okay to use), RCA "black ribbed plate", RCA "clear tops", German Telefunken ECC82s but these are really expensive.....I have only 1 pair.